Reaming and counterboring bit



E. A, BENSQN Feb. 16, 1932.

HEARING AND COUN TERBORING BIT Filed Oct. 22, 1930 I INVENTOR.

Patented Feb. 16, 1932 UNITED STATES EDWIN A. BENSON, OF OAKLAND, CALIFORNIA REAMING AND cooivrnanonnve BIT Application filed. October 22, 1930. Serial'No. 490,487.

This invention relates to a bit for reaming and counterboring or counter-sinking previously formed bores.

An object of the invention is to provide a bit of the character described which may be operated with greater easecand accuracy by reason of a new form of guide means arranged to have a bit-centering and guiding fit in the bore to be reamed or countersunk.

Another object is to provide abit of the character described in whicl the cutter is adjustably held in place by a simple and inexpensive means consisting of comparatively few parts.

A further object is to provide a bit of the character described wherein the guide means serves in a particularly eflicacious manner. for locking the cutter in adjusted position.

Still another object is to provide a bit of the character described which is comprised of comparatively few parts and designed and arranged so as to be strong, durable and compact, while at the same time easier to operate, less expensive and more accurate than similar bits heretofore provided.

The invention possesses other objects and features of advantage some of which, with the foregoing, will be set forth or be apparent in the following description of a preferred embodiment of the device, and in the accompanying drawings, in which,

Fig. 1 is a side elevation of the bit of this invention.

Fig. 2- is an enlarged fragmentary sectional view taken thru the head and nose of the bit with the cutter removed.

Fig. 3 is a sectional view similar to but taken at right angles to Fig. 2, nose members for use with the bit being removed.

Fig. i is a schematic view of toe cutter unit showing the assembly of the adjusting and locking means therefor.

Fi g. 5 is a perspective view showing one of the guide cylinders as when arranged to lock the cutter, which latter is indicated in dotted lines.

The present embodiment of this invention as shown in detail in the accompanying drawings is seen to comprise a shank 6 of the usual form a bithead 7 adj'ustably supporting a cutter bar,8,'a cutter adjusting screw 9, and a combined guide nose and cutter holding or locking means 10.

'The head 7 .is of generally cylindrical form but is flattened on one side and there provided with a transverse groove or recess 11 for receiving the cutter 8. It will be noted that the groove and cutter are mutually dovetailedand that'the lower beveled face 12 of the groove extends along only an intermediate portion of the groove whereby thelower edge face of the cutteris exposed at opposite ends of the groove in order to be engaged and locked-by the means 10 as will be later described. The opposite wall of the groove 11 intersects a transverse bore 12 containing the cutter adjusting screw 9 which latter is rotatablyheld in'place bya screw 13. By this arrangement, the screw 9 is disposed to engagerack teeth Mon the upper edge of the cutter and, on appropriate rotation of the screw with a suitable tools not shown, the cutter radius may be'adjusted as desired.

The guide-means 10 "comprises a cylindrical body portion 16 formed as an integral extension of the head 7 and axially alined with the shank 6, a screw 17 threadedly engaged in an axial bore 18 thru the portion 16, and a plurality of mutually nested cup-like members 19 of cylindrical outline removably mounted on said portion 16.

The portion 16 without the cylinder members 19 thereon is adaptedfto be inserted into a relatively small bore of standard diameter, to guide and serve as bearing for the tool when reaming or counterboring said bore. The cutter8 at this time is held or locked by the upper end of the screw 17 engaging in the groove 20 in the lower edge 'ofthe cutter. 1

However when one or more of the-cylinders 19 are used, as for reaming or counter-boring larger bores, "the number of said cylinders used depends on the diameter of the initial bore, and the screw 17 then serves only as ameans for holding such cylinders in place and causing them to bind against and lock the cutter. In this connection it will be noted that each cylinder is provided at m its inner and free edge with a pair of outwardly projecting locking lugs 21 arranged to engage in the groove in the cutter 8. Owing to this arrangement not only are the cylinders held against rotation but also securely hold the cutter against unintentional movement out of its adjusted position. The holding action of these cylinders is regulated by the screw 17 which it is noted passes thru openings 22 in the closed ends 23 of the cylinders. with its head 24 disposed to bear upon the outer said closed end. The length of the innermost cylinder is such that the closed end is spaced from the outer end of the portion 16 when the other end of said cylinder is engaged with the cutter. and this clearance insures adequate longitudinal movement of the cylinders to permit the described locking en agement thereof with the cutter.

The bevel 25 at the lower end of each cylinder provides for an easy entrance of the guide nose into the bore to be reamed or countersunk.

It will be clear that by providing the plurality of cylinders 19 the guide nose may be quickly and easily increased or decreased as to its diameter to fit in bores of various diameters, and that the relatively long bearing surface provided by said nose in the bore will insure a smooth and accurate reaming or connterboring action.

The use of the particular guide or bearing nose of this invention also minimizes the number of parts required for holding or locking the cutter in place, and in general simplifies and reduces the cost of the tool as well as otherwise improving it.

I claim:

In a device of the character described. a bit head, a cutter slidably mounted in the head for transverse adiustment with relation to the head. sa d cutter having a wedge sh aned groove formed lengthwise of its lower edge, a complementary projection on the bit head engaging said groove, anintegrally formed cylindrical projection on the lower end of the head. a plurality of cylinders tele copically and removably mounted on said head, wedge shaped projections on the upper edge of each cylinder engageable with said groove and the screw in the lower end of said cylindrical projection adapted to maintain said cylinders in position thereon and force said wedge shaped projections into the wedge shaped groove, said screw having a beveled end thereon for engagement with the wedge shaped groove when said cylinders are removed.

EDWIN A. BENSON. 

